This invention relates to reciprocating piston engines, and more particularly those reciprocating piston engines that translate a reciprocating linear movement of a piston into a circular or rotational movement of a crankshaft so as to impart power out of the engine.
Previous classes of piston engines relied upon a piston with a single combustion chamber, such as the device taught in U.S. Pat. No. 1,636,612 to NOAH, issued Jul. 19, 1927, entitled “Internal-combustion engine.” More efficient double-ended pistons, such as that taught in U.S. Pat. No. 4,941,396 to MCABE, issued Jul. 17, 1990, entitled “Reciprocating double-ended piston,” rely upon a design that reduces the size and number of component parts for a piston engine.
There are numerous designs for translating the linear motion of a piston into a rotational motion. Generally, single ended pistons translate the linear piston motion into rotational motion through a connecting rod attached to a crankshaft, with the connecting rod imparting rotational motion to the crankshaft. This design, however, is not the most efficient means of imparting rotational motion upon a crankshaft. The number of connecting and moving parts reduces the overall efficiency of the engine.
In an attempt to gain more efficiency and power with less space, internal combustion engines have been designed with double-ended pistons, such as those disclosed in U.S. Pat. No. 1,776,895 to GEORGE, issued Sep. 30, 1930, entitled “Double-acting internal-combustion engine,” U.S. Pat. No. 2,094,830 to DAVID, issued Oct. 5, 1937, entitled “Multiple cylinder engine,” U.S. Pat. No. 2,304,407 to HOGAN, issued Dec. 8, 1942, and U.S. Pat. No. 2,335,252 to APPEMAN, issued Nov. 30, 1943, entitled “Internal combustion engine.”
A double-ended piston, with combustion chambers located at each end of the piston, however, requires that the linear motion be translated from the piston in a different manner than that employed in a cylinder with a single combustion chamber. Numerous designs have attempted to solve the problem of translating the linear motion of a double-ended piston into rotational motion. Some devices have translated the linear motion to a crankshaft through connecting means that is located to the side of the cylinder, extending crosswise to the axis of the cylinder, such as those in U.S. Pat. No. 2,304,407 to HOGAN, issued Dec. 8, 1942, and U.S. Pat. No. 2,335,252 to APPEMAN, issued Nov. 30, 1943, entitled “Internal combustion engine.”
In an effort to reduce the complexity of existing piston designs as well as reduce the vibrations from periodic unbalanced vertical inertial forces of pistons and connecting rods and lateral inertia forces created by crankshaft counterweights during rotation of the crankshaft, means were devised to have a crankshaft in direct mechanical contact with the piston. For example, the device taught in U.S. Pat. No. 4,485,768 to Heniges, issued Dec. 4, 1984, entitled “Scotch yoke engine with variable stroke and compression ratio,” employs a variation of what is commonly referred to as a Scotch Yoke. The Scotch Yoke is also the subject of the devices disclosed in U.S. Pat. No. 5,331,926 to Vaux et al., issued Jul. 26, 1994, entitled “Dwelling scotch yoke engine,” and U.S. Pat. No. 5,640,881 to Brackett, issued Jun. 24, 1997, entitled “Motion converter with pinion sector/rack interface.” The Scotch Yoke, however, tends to cause wear on the slot in which the crankshaft runs through the piston. In addition, the linear motion of the piston is imparted upon the crankshaft and translated into rotational motion through gearing or some other mechanical means by the crankshaft. The solution taught in U.S. Pat. No. 4,485,769 to Carson, issued Dec. 4, 1984, entitled “Engine,” discloses a central hole through which a crankshaft rotates. However, that design requires counterbalancing to keep the crankshaft balanced within the piston rod, and does not provide a constant, solid mechanical engagement between the piston and the crankshaft.
What is needed, therefore, is a means to provide rotational motion directly onto the crankshaft without complicated devices or linkages that can cause power losses and include a large number of parts that can wear, break, and need lubrication. The new device should, as well, provide a continuous mechanical engagement between the crankshaft and the piston.